NFL All Star - Lesson 02 - Defense vs. Position Stats

Daily fantasy football is a game of exploiting matchups. That’s ultimately what everything comes down to: figuring out which players have the best matchups and will see the workload/efficiency to give you production that exceeds their cost.

There are a lot of ways to analyze matchups, some better than others. The most common is to view a defense’s overall run or pass defense rank, usually in terms of scoring or yards allowed, and then apply it to an entire offense. Most players look at a defense’s pass rank when choosing both wide receivers and tight ends, for example. There’s a clear problem with that; namely, that specific defenses tend to be stronger/weaker against particular positions.

Thus, defense versus position stats are what we really need to analyze. If I’m projecting Rob Gronkowski in a given week, I don’t really care how the opposing defense performs as a whole, even against the pass; I just want to know how many opportunities Gronk will see against the middle of their defense and how efficient he can be with his targets.

With that said, there are a lot of different defense vs. position stats out there. Here’s where to start.

START WITH EFFICIENCY

First and foremost, I think it’s vital to make sure we’re using the right basic stats. Analyzing total yards or points allowed is going to be misleading in many cases because we could get fooled by a team’s prior game scripts.

Here’s an example. It’s Week 5 and Cowboys are facing off against the Packers and we want to project Dez Bryant. Green Bay has been in a bunch of shootouts thus far into the season and their pass defense has surrendered a ton of yards. They’re ranked 20th in the league in yards allowed.

But here’s the thing: the Packers have been on the field a whole lot more than usual and actually rank in the top 10 in net-YPA allowed to opposing offenses when targeting receivers. They’re getting killed by the run in terms of efficiency, but haven’t been run on very much, making it look like their run defense is better than it is.

This is a perfect example of how a change in future game flow would impact a player. In this case, we might expect Dallas to run all over Philly, limiting Bryant’s targets. And if we think the Green Bay secondary is better than their bulk stats suggest, it could be the case that Bryant is overpriced relative to the actual quality of his matchup.

The point is this: don’t study stats (like yards allowed) that combine both opportunities and efficiency. You should always be separating those two, thinking about how a game might unfold, projecting the stats separately, and then combining them later.

THE BEST STATS

So where are the best DvP stats for football? I think the two best sources are Pro Football Focus and Football Outsiders. The former breaks down game film and sorts every play into a number of categories, grading players and tracking valuable data. When a cornerback is injured and I want to see how well his backup has played, Pro Football Focus is where I go.

Pro Football Focus also has very objective stats like yards per target or yards per route allowed, as well as where players line up. Some cornerbacks stay on one side of the field, for example, while others shadow an opposing receiver. I love to use PFF to determine which cornerbacks are going to be matched up on which wide receivers on the majority of snaps.

At Football Outsiders, they do a really nice job of separating position/team strength from prior matchups. It really helps to see how offenses or defenses or position units stack up after adjusting for opponent quality, which really helps with making predictions.

HOW DEFENSIVE QUALITY AFFECTS PRODUCTION

Another thing to keep in mind is that defensive quality affects production differently at each position. Due to sample size, week-to-week variance, and the nature of each position, some spots are more likely to beat a top defense than others. Additionally, there seems to be a larger deviation in stats for passers.

Running backs are the most matchup-dependent position; when they face a bottom 10 run defense, you can be more sure they’re going to be valuable than when a wide receiver faces a top 10 pass defense. And vice versa; running backs tend to struggle against top 10 run defenses.

Production from tight ends have historically come almost independently of the matchup. That could be due to errors in the way we assess tight end matchups, but you should really care most about matchups for running backs and least for tight ends.

UNDERSTANDING VARIANCE

With any football stat, it’s always important to remember there’s often a high level of variance in the results. Because of the limited number of games, many stats—defense vs position stats included—can be pretty noisy, especially in the beginning of the year.

The way to take advantage of that is to look for instances when a defense’s stats aren’t really reflective of their talent. If a mediocre defense starts the year with three easy matchups and shuts down the opposing offenses, their defense versus position stats will probably look a whole lot better than what we should expect moving forward. It’s especially useful to target opposing players against defenses like these in tournaments because ownership will often be down when it shouldn’t be.

PASS RUSH MATTERS

The last thing I want to say in regards to defense versus position stats is that the pass rush matters a whole lot. I’ve done a lot of research on this and found that secondary play is actually better predicted with past defensive line play than it is with past secondary play, i.e. cornerbacks and safeties are extremely reliant on a quality pass rush.

That means that one of the most devastating injuries to a defense that will significantly affect their pass defense is one to a quality pass-rusher. When a top defensive end goes down, for example, you can expect their cornerbacks and pass defense as a whole to struggle quite a bit.

In this way, it’s important to keep in mind that football is a holistic game. We can never truly separate a player or position from the rest of his team; they all work in conjunction. An injury to a left guard affects everyone else on the field. The center might need to help the backup left guard more, exposing the right side of the line, which in turn hurts the running back, quarterback, and receivers.

Thus, we can’t just look at a secondary and say they’re going to play at X level no matter what, and in fact, the most important part of projecting your receivers in many cases might not be analyzing the opposing cornerbacks, but rather the opposing pass rush.

 


I am a promoter at DraftKings and am also an avid fan and user (my username is Bales) and may sometimes play on my personal account in the games that I offer advice on. Although I have expressed my personal view on the games and strategies above, they do not necessarily reflect the view(s) of DraftKings and I may also deploy different players and strategies than what I recommend above.